Systems and methods for creating a lesion using transjugular approach

ABSTRACT

A method of treating a tissue region includes inserting a flexible sheath within a vessel, the vessel leading to a tissue region, placing a distal end of the sheath through a wall of the vessel to thereby position the distal end is at or adjacent the tissue region, deploying a plurality of electrodes from the distal end of the sheath such that tips of the deployed electrodes approximately face towards a proximal end, and delivering energy to the tissue region using the deployed electrodes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of copending U.S. application Ser.No. 12/582,561, filed on Oct. 20, 2009, which in turn is a continuationof U.S. application Ser. No. 11/168,234, now U.S. Pat. No. 7,615,050,filed on Jun. 27, 2005. The entire disclosure of each of the foregoingreferences is incorporated by reference herein for all purposes.

BACKGROUND

1. Field

The field of the invention relates to medical devices, and moreparticularly, to medical devices and methods of their use for treatingtumors or other targeted bodily tissue using electrical energy.

2. Background

Tissue may be destroyed, ablated, or otherwise treated using thermalenergy during various therapeutic procedures. Many forms of thermalenergy may be imparted to tissue, such as radio frequency electricalenergy, microwave electromagnetic energy, laser energy, acoustic energy,or thermal conduction.

In particular, radio frequency ablation (RFA) may be used to treatpatients with tissue anomalies, such as liver anomalies and many primarycancers, such as cancers of the stomach, bowel, pancreas, kidney andlung.

RFA treatment involves the destroying undesirable cells by generatingheat through agitation caused by the application of alternatingelectrical current (radio frequency energy) through the tissue.

Various RF ablation devices have been suggested for this purpose. Forexample, U.S. Pat. No. 5,855,576 describes an ablation apparatus thatincludes a plurality of wire electrodes. Each of the wires includes aproximal end that is coupled to a generator; and a distal end that mayproject from a distal end of a cannula. The wires are arranged in anarray with the distal ends located generally radially and uniformlyspaced apart from the catheter distal end. The 5 wires may be energizedin a monopolar or bipolar configuration to heat and necrose tissuewithin a precisely defined volumetric region of target tissue. Thecurrent may flow between closely spaced wire electrodes (bipolar mode)or between one or more wire electrodes and a larger, common electrode(monopolar mode) lOcated remotely from the tissue to be heated. Toassure that 10 the target tissue is adequately treated and/or to limitdamaging adjacent healthy tissues, the array of wires may be arrangeduniformly, e.g., substantially evenly and symmetrically spaced-apart sothat heat is generated uniformly within the desired target tissuevolume. Such devices may be used either in open surgical settings, inlaparoscopic procedures, and/or in percutaneous interventions.

Currently, tumor near a vessel may be difficult to ablate. This isbecause the vessel continuously provide blood to the tumor during anablation procedure, thereby carrying heat away from a targeted region.As a result, it may be difficult to achieve a complete burn for thetumor near the vessel.

SUMMARY

In accordance with some embodiments, a method of treating a tissueregion includes inserting a flexible sheath within a vessel, the vesselleading to a tissue region, placing a distal end of the sheath through awall of the vessel to thereby position the distal end at or adjacent thetissue region, deploying a plurality of electrodes from the distal endof the sheath such that tips of the deployed electrodes approximatelyface towards a proximal end, and delivering 5 energy to at least aportion of the tissue region using the deployed electrodes.

In accordance with other embodiments, a system for treating tissuewithin a tissue region using electrical energy includes a flexiblesheath having a proximal end, a distal end, and a body extending betweenthe proximal and the distal ends, wherein the body is sized such that itcan be placed within a blood vessel, and has a length such that whenplaced within the blood vessel, the proximal end is outside a patient'sbody and the distal end is adjacent the tissue region, and an array ofelectrodes slidably disposed within a lumen of the sheath, wherein thesheath further has a sharp distal tip for puncturing a vessel.

In other embodiments, a system for treating tissue within a tissue 15region using electrical energy includes a flexible sheath having aproximal end, a distal end, and a body extending between the proximaland the distal ends, wherein the body is sized such that it can beplaced within a blood vessel, and has a length such that when placedwithin the blood vessel, the proximal end is outside a patient's bodyand the distal end is adjacent the tissue region, a shaft 20 having abody, the body having a wall and a plurality of openings through thewall, and an array of electrodes coupled to the shaft, and slidablydisposed within a lumen of the sheath.

Other aspects and features will be evident from reading the followingdetailed description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of the illustratedembodiments, in which similar elements are referred to by commonreference numerals. In order to better appreciate how advantages andobjects of the embodiments are obtained, a more particular descriptionof the embodiments is illustrated in the accompanying drawings.

FIG. 1 illustrates a system for delivering electrical energy to tissuein accordance with some embodiments.

FIG. 2 is a cross-sectional side view of an embodiment of an ablationdevice, showing electrode tines constrained within a sheath.

FIG. 3 is a cross-sectional side view of the ablation device of FIG. 2,15 showing the electrode tines deployed from the sheath.

FIG. 4 illustrates a system for delivering electrical energy to tissuein accordance with other embodiments.

FIGS. 5A-5D are cross-sectional views, showing a method for treatingtissue, in accordance with some embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows an ablation system 10, in accordance with some embodiments.The ablation system 10 includes a source of energy 12, e.g., a radiofrequency (RF) generator, and an ablation device 18 configured to be 5coupled to the generator 12 via a cable 20 during use.

The generator 12 is preferably capable of operating with a fixed orcontrolled voltage or current so that power and current diminish asimpedance of the tissue being ablated increases. Exemplary generatorsare described in U.S. Pat. No. 6,080,149, the disclosure of which isexpressly incorporated by 10 reference herein. The preferred generator12 may operate at relatively low fixed voltages, typically below onehundred fifty volts (150 V) peak-to-peak, and preferably between aboutfifty and one hundred volts (50-100 V). Such radio frequency generatorsare available from Boston Scientific Corporation, assignee of thepresent application, as well as from other commercial suppliers. Itshould 15 be noted that the generator 12 is not limited to those thatoperate at the range of voltages discussed previously, and thatgenerators capable of operating at other ranges of voltages may also beused.

Turning to FIGS. 2 and 3, in the illustrated embodiments, the ablationdevice 18 of FIG. 1 is a ablation assembly 50 that includes a sheath 52having a 20 lumen 54, a shaft 56 having a proximal end 58 and a distalend 60, and a plurality of electrode tines (or wires) 62 secured to thedistal end 60 of the shaft 56. The proximal end 58 of the shaft 56 mayinclude a connector (not shown) for coupling to the generator 12.Alternatively, the ablation assembly 50 may itself include a cable (notshown) on the proximal end 58 of the shaft 56, and a connector may beprovided on the proximal end of the cable (not shown).

In the illustrated embodiments, the sheath 52 has a length between 5about forty and one hundred and thirty centimeters (40-130 cm), and morepreferably, between sixty and eighty (60-80 cm). Also, the sheath 52 hasan outer diameter or cross sectional dimension between about one andfive millimeters (1-5 mm), and more preferably, between two and fourmillimeters (2-4 mm). In one implementation, the sheath 52 is configured(e.g., sized and 10 shaped) such that it can be inserted within a vessel(e.g., a jugular vein), and that a body of the cannula 52 can extendbetween a proximal end 72 located outside a patient's body and a distalend 70 located at or adjacent a target region, e.g., a liver, when thesheath 52 is inserted into a jugular vein. In other embodiments, thesheath 52 may also have other lengths and outer cross sectionaldimensions, 15 depending upon the application. The sheath 52 may beformed from a polymer, and the like, as long as it is sufficientlyflexible for allowing the sheath 52 to be steered through a vessel. Thesheath 52 may be electrically active or inactive, depending upon themanner in which electrical energy is to be applied.

The sheath 52 coaxially surrounds the shaft 56 such that the shaft 56 20may be advanced axially from or retracted axially into the lumen 54 ofthe sheath 52. The shaft 56 can be made from any of a variety of elasticmaterials, such as a polymer, or a metal, as long as it is sufficientlyelastic to be steered through a vessel. For example, the shaft 56 can bea Nitinol tube having a plurality of openings for providing a desiredflexibility for the tube, which is available at Boston ScientificCorporation, the Precision Vascular Division. In other cases, instead ofbeing a tube, the shaft 56 can have a solid cross-section. Optionally, a5 handle 64 may be provided on the proximal end 58 of the shaft 56 tofacilitate manipulating the shaft 56. The electrode tines 62 iscompressed into a low profile when disposed within the lumen 54 of thesheath 52, as shown in FIG. 2.

As shown in FIG. 3, the proximal end 58 of the shaft 56 or the handle 64(if one is provided) can be advanced to deploy the wires 62 from thelumen 54 of the 10 sheath 52. When the electrode tines 62 are unconfinedoutside the lumen 54 of the sheath 52, they assume a relaxed expandedconfiguration. FIG. 3 shows an exemplary two-wire array includingelectrode tines 62 biased towards a generally “U” shape andsubstantially uniformly separated from one another about a longitudinalaxis of the shaft 56. Alternatively, each electrode tine 62 may have 15other shapes, such as a “J” shape, a flare shape, a bent shape, aparabolic shape, and/or the array may have one electrode tine 62 or morethan two electrode tines 62. The array may also have non-uniform spacingto produce an asymmetrical lesion. In some embodiments, the electrodetines 62 are formed from spring wire, superelastic material, or othermaterial, such as Nitinol, that 20 may retain a shape memory. During useof the ablation assembly 50, the electrode tines 62 are deployed into atarget tissue region to deliver energy to the tissue to create a lesion.Ablation devices having a spreading array of electrode tines have beendescribed in U.S. Pat. No. 5,855,576, the disclosure of which isexpressly incorporated by reference herein.

Optionally, a marker (not shown) may be placed on the handle 64 and/oron the proximal end 58 of the shaft 56 for indicating a rotational 5orientation of the shaft 56 during use. In other embodiments, theablation assembly 50 may also carry one or more radio-opaque markers(not shown) to assist positioning the ablation assembly 50 during aprocedure, as is known in the art. For example, in some embodiments, theablation assembly 50 may further include a radio opaque marker locatedat a distal end 70 of the sheath 52 10 or the shaft 56. Alternatively oradditionally, one or more of the electrode tines 62 may each carry aradio opaque element (e.g., a marker). Optionally, the ablation assembly50 may also include a sensor, e.g., a temperature sensor and/or animpedance sensor (not shown), carried by the distal end of the shaft 56and/or one or more of the electrode tines 62. In such cases, the energysource 15 12 may be configured to control an amount of energy deliveredto the electrode tines 62 based at least in part on a signal provided bythe sensor.

In the illustrated embodiments, the ablation assembly 50 further includea steering mechanism 80 secured to the proximal end 72 of the sheath 52for steering a distal end 70 of the sheath 52. The steering mechanism 8020 includes a rotatable cam and one or more steering wires (not shown)connected between the cam and the distal end 70 of the sheath 52. Duringuse, the cam can be rotated to apply tension to a steering wire, therebycausing the distal end 70 of the sheath 52 to bend. Further detailsregarding the steering mechanism 80 are described in U.S. Pat. No.5,273,535, the entire disclosure of which is herein incorporated byreference. Steering devices that can be used with the ablation assembly50 have also been described in U.S. Pat. Nos. 5,254,088, 5 5,336,182,5,358,478, 5,364,351, 5,395,327, 5,456,664, 5,531,686, 6,033,378, and6,485,455, the entire disclosures of which are expressly incorporated byreference herein.

In other embodiments, the ablation assembly 50 does not include thesteering mechanism 80. In such cases, a separate introducer sheath or 10introducer catheter may be used to gain access through a vessel. Theintroducer sheath may have a pre-bent distal end for assisting steeringthrough a vessel. Alternatively, the introducer sheath may be steeredusing a guidewire in a conventional manner, or may include a steeringmechanism, such as the steering mechanism 80 discussed previously, forsteering its distal end. In some 15 embodiments, the introducersheath/catheter can have a sharp distal tip for piercing tissue.

In other embodiments, the ablation assembly 50 can include a guidewire(not shown) to assist placement of the distal end 70 of the sheath 52 ina conventional manner. The guidewire may be located within the lumen 54of the 20 sheath 52, or alternatively, located within another lumen (notshown) in the sheath 52 that is parallel to the lumen 54.

It should be noted that the ablation device 18 is not necessarilylimited to the ablation assembly 50 shown in FIGS. 2 and 3, and that theablation device 18 may be selected from a variety of devices that arecapable of delivering ablation or therapeutic energy. For example,medical devices may also be used 5 that are configured for deliveringultrasound energy, microwave energy, and/or other forms of energy forthe purpose of ablation, which are well known in the art.

In the illustrated embodiments, the ablation assembly 50 also includesan electrode 90 secured to the sheath 52. A wire (not shown) may bedisposed within the wall of the sheath 52 to electrically couple theelectrode 90 to the 10 generator 12 during use. The electrode 90 and thearray of electrodes 62 are connected to opposite terminals of thegenerator 12 for delivering energy to target tissue in a bipolar mode.In other embodiments, the ablation assembly 50 does not include theelectrode 90 (FIG. 4). In such cases, the system 10 further includes anelectrode pad 92 electrically coupled to the generator 12. The 15electrode pad 92 functions as a return electrode, and operates inconjunction with the ablation assembly 50 to deliver energy to targettissue in a monopolar mode. [0027] Referring now to FIGS. 5A-5D, theablation system 10 may be used to treat at least a portion, e.g., atarget tissue TS, within a treatment region TR 20 within tissue Tlocated beneath skin or an organ surface S of a patient. First, if anintroducer sheath/catheter 100 is provided, the introducer sheath 100can be inserted through a patient's skin and into a vessel V. Theintroducer sheath 100 is then steered through the vessel V in aconventional manner (e.g., using a guidewire or a steering mechanism)until its distal end 102 is at or adjacent to the treatment region TR.As shown in FIG. 5A, the sharp distal tip of the introducer sheath 100can then be used to puncture the vessel V to gain access to the 5treatment region TR. Next, the ablation assembly 50 is inserted into theintroducer sheath 100, and is advanced until the distal end 70 of thesheath 52 of the ablation assembly 50 reaches the treatment region TR(FIG. 5B). [0028] In other embodiments, instead of using an introducersheath/catheter 100, if the ablation assembly 50 includes the steeringmechanism 80, the 10 ablation assembly 50 can be inserted through apatient's skin and into the vessel V, and be steered to a desiredlocation at or adjacent to the target region TR. In one implementation,a transjugular approach may be used, in which the distal end 70 isinserted through a jugular vein in the patient's neck. After the distalend 70 of the sheath 52 has been inserted through the patient's skin,the distal 15 end 70 is then steered to the tissue T, such as a livertissue, through the vessel V. The sheath 52 may be steered by using theguidewire in a conventional manner, or by applying tension to steeringwire(s) (if the steering mechanism 80 is provided). If the sheath 52 hasa sharp distal tip, it can be used to puncture the vessel V to allow thedistal end 70 of the sheath 52 to gain access to the 20 target regionTR. In other embodiments, a separate puncturing device, such as a wireor a needle, can be inserted through the sheath 52 to puncture thevessel V.

Turning to FIG. 5C, after the sheath 52 is properly placed, the shaft 56of the ablation assembly 50 is then advanced distally, thereby deployingthe array of electrode tines 62 from the distal end 70 of the sheath 52into the target tissue TS at the target region TR. As illustrated,delivering the electrode tines 62 5 via the vessel V that leads to thetarget region TR is advantageous in that, if any bleeding occurs at thetarget region TR, it will do so back into the vessel V. In theillustrated embodiments, the electrode tines 62 are deployed such theelectrode tines 62 are located in close proximity (e.g., within 0.1millimeter (mm) to 10 mm) to the vessel V. In such arrangement, thedistal ends of the electrode 10 tines 62 are positioned among or aroundsub-branches (not shown) of the vessel V, thereby allowing ablationenergy to be effectively delivered to the target tissue TS whileminimizing, or at least reducing, the effect of the heat sink due toblood delivered to or from the target region TR. As shown in the figure,the distal ends 63 of the deployed electrode tines 62 are distal to thedistal end of the vessel V.

Alternatively, the distal ends 63 of the deployed electrode tines 62 maybe proximal to the distal end of the vessel V such that the deployedelectrode tines 62 at least partially circumscribe a portion of thevessel V. Preferably, the electrode tines 62 are biased to curveradially outwardly as they are deployed from the sheath 52. The shaft 56of the ablation device 18 may be advanced 20 sufficiently such that theelectrode tines 62 fully deploy to circumscribe substantially tissuewithin the target tissue TS of treatment region TR, as shown in FIG. 5D.Alternatively, the electrode tines 62 may be only partially deployed ordeployed incrementally in stages during a procedure.

Next, energy, preferably RF electrical energy, may be delivered from thegenerator 12 to the wires 62 of the ablation device 18, therebysubstantially 5 creating a lesion at the target tissue TS of thetreatment region TR. If the system of FIG. 1 is used, the electrode 90and the electrodes 62 will operate to deliver ablation energy in abipolar mode. In such cases, ablation energy will flow between theelectrode 90 and the array of electrodes 62. Alternatively, if thesystem of FIG. 4 is used, the electrode pad 92 may be coupled to theopposite 10 terminal (not shown) of the generator 12, and is placed onthe patient's skin in a Conventional manner. In such cases, ablationenergy will flow between the electrode pad 92 and the electrodes 62,thereby delivering ablation energy in a monopolar manner. As shown inthe figure, the deployed electrodes 62 have distal ends 63 that point atleast partially towards a proximal end (e.g., a 15 component of thevector representing the direction in which the distal ends 63 point istowards a proximal end—e.g., towards the vessel V). Such configurationallows the ablation energy to be effectively delivered to the targettissue TS while minimizing, or at least reducing, the heat sink effectresulted from blood flowing to or from the vessel V.

When a desired lesion at the target tissue TS of the treatment region TRhas been created, the electrode tines 62 of the ablation device 18 maybe retracted into the lumen 54 of the sheath 52, and the ablation device18 may be removed from the treatment region TR. In some cases, theentire treatment region TR may be ablated in a single pass. In othercases, if it is desired to perform further ablation to increase thelesion size or to create lesions at different site(s), e.g., at othertarget tissue TS, within the treatment region TR or 5 elsewhere, theelectrode tines 62 of the ablation device 18 may be introduced anddeployed at different target site(s), and the same steps discussedpreviously; may be repeated.

Although particular embodiments have been shown and described, it willbe understood that it is not intended to limit the present inventions tothe 10 preferred embodiments, and it will be obvious to those skilled inthe art that various changes and modifications may be, made withoutdeparting from the spirit and scope of the present inventions. Forexample, the electrode tines 62 may be a single electrode made from aplurality of conductive components, or a plurality of electrodes. Assuch, the term, “a plurality of electrodes” should not be limited 15 tomore than one electrode, and may include a single electrode having aplurality of conductive components/parts. The specification and drawingsare, accordingly, to be regarded in an illustrative rather thanrestrictive sense. The present inventions are intended to coveralternatives, modifications, and equivalents, which may be includedwithin the spirit and scope of the present inventions as defined by theclaims.

1-21. (canceled)
 22. A method of treating a tissue region, comprisingthe steps of: inserting a flexible sheath within a blood vessel, theblood vessel leading to a tissue region; placing a distal end of thesheath adjacent to the tissue region; extending an electrode from thedistal end of the sheath such that a portion of the electrode is located0.1-10 mm from a wall of the blood vessel; and delivering energy to thetissue region using the deployed electrode, wherein (a) the electrode isdispensed at a distal end of a shaft slidably disposed within thesheath, (b) the step of extending the electrode from the distal end ofthe sheath includes advancing the shaft distally relative to the sheath,(e) the shaft is attached to a handle, the handle configured to move theshaft axially and rotationally, and (d) at least one of the shaft andthe handle includes a visual indicator of a rotational orientation ofthe electrode.
 23. The method of claim 22, wherein the electrode has acurved shape when extended from the sheath.
 24. The method of claim 23,wherein the electrode curves radially outwardly when extended from thesheath.
 25. The method of claim 22, further comprising the step ofchanging a rotational orientation of the electrode.
 26. The method ofclaim 25, further comprising the step of changing an axial position ofthe electrode.
 27. The method of claim 22, wherein the tissue region ispart of a kidney.
 28. The method of claim 22, wherein the electrodeincludes a plurality of conductive elements.
 29. The method of claim 28,wherein the energy is RF energy and is delivered from one or more of theplurality of conductive elements.
 30. The method of claim 22, whereinthe electrode includes radiopaque material.
 31. The method of claim 22,wherein the sheath includes a radiopaque material.
 32. The method ofclaim 22, wherein the electrode includes a sensor capable of sensing atemperature or an impedance, and the step of delivering energy to thetissue region includes varying the energy delivered based at least inpart on a signal provided by the sensor.
 33. A system for treating atissue comprising: as electrode disposed at a distal end of a flexibleshaft; a sheath slidably disposed over the flexible shaft; and a handleconnected to each of the sheath and the flexible shaft, the handleconfigured to move the shaft axially and rotationally relative to thesheath, wherein at least one of the handle and the sheath includes avisual indicator of a rotational orientation of the shaft.
 34. Thesystem of claim 33, wherein the electrode has a curved shape whenextended from the sheath.
 35. The system of claim 33, wherein theelectrode curves radially outwardly when extended from the sheath. 36.The system of claim 33, wherein the electrode includes a plurality ofconductive elements.